The present invention relates generally to machine tools and, more particularly, to new and improved cut-off and/or grooving tool parts therefor and methods of making same.
The art is replete with machine tools such as lathes and the like adapted to rotate a workpiece for machining a groove on the inner diameter, the outer diameter or the end face of the workpiece or even to cut completely through a solid bar. In such machines, a tool bit insert, formed with a sharp cutting edge and made of hardened material such as tungsten-carbide, is mounted to a relatively massive shank by a head assembly which is supposed to positively locate the cutting edge of the tool bit insert relative to a predetermined reference position (usually the bottom surface) of the shank. The shank is then securely placed in the machine wherein the workpiece and the cutting edge are brought together so that as the workpiece is rotated, a groove is cut in the workpiece or, if the cutting edge "travels" to the center of the workpiece, a portion of the workpiece is completely cut off.
Numerous designs have been developed for head assemblies intended to achieve certain desirable characteristics in the tool. For example, some head assemblies are particularly designed to ensure that the cutting is squared relative to certain reference parts. Other designs are intended to permit adjustment of the cutting edge. However, in most, if not all, of these designs, numerous parts (usually at least a back-up plate behind the insert) are used for locating the cutting edge. Although such configurations have provided satisfactory results in some applications, they do suffer certain drawbacks, particularly in view of the multiple surfaces abutting one another seriatim, which could cause the resultant position of the cutting edge to be outside the acceptable range of tolerances.
Recently, with the advent of computerized tooling, certain uniform standards have been developed for locating the cutting edge relative to a predetermined reference and it is critical that the cutting edge be positioned within prescribed tolerances. The most widely used standard is that developed by A.N.S.I. which locates the outer end point of the cutting edge relative to the bottom surface of the shank by the combination of its distance (designated "B", the cutting height) above that surface, by its distance (the "C" dimension) from the back edge (or butt) of the shank and by its distance (the "F" dimension) from the opposite side of the shank. Although tool parts have been made and qualified to A.N.S.I. standards, there has been no tooling assembly (i.e., head assembly and shank combination) which enables easy interchange of one cutting edge with another without having to re-set, or re-qualify, the tooling assembly according to the A.N.S.I. standard. Similarly, there is no tooling assembly in which head assemblies are interchangeable on a particular shank with the resultant tooling assembly still A.N.S.I. qualified nor is there a tooling assembly which permits easy replacement of damaged tool bit inserts.
Notwithstanding the A.N.S.I. standards, it is important that the support capability provided by the head assembly is sufficiently strong to prevent a portion of the head assembly from being broken due to shear forces generated during the tooling operation. It is also important that the mounting means between the shank and the head assembly be sufficiently strong to prevent the head from being sheared off the shank.
Accordingly, it is an object of the present invention to provide new and improved tooling parts and method for making same. It is also an object of the invention to provide new and improved tooling parts and method for making same, whereby a strong tooling assembly is provided with a minimum number of component parts.
It is another object of the invention to provide new and improved tooling parts and method for making same, which enables interchangeability of tool bit head assemblies on any shank.
It is a further object of the invention to provide new and improved tooling parts and method for making same, which enables interchangeability of tool bit head assemblies (at least for head assemblies intended to perform the same function--i.e., grooving or cut-off) on any given shank with automatic qualification to A.N.S.I., or any other similar standards.
It is yet another object of the invention to provide new and improved tooling parts and method for making same, which provides sufficiently strong support for the tool bit insert to withstand the forces generated during operation of the machine tool. Further, the tooling parts are to include attachment means for mounting the head assembly to the shanks, adapted to prevent relative rotational movement, or "chattering", therebetween.
Objects and advantages of the invention are set forth in part herein and in part will be appreciated herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the methods, steps, instrumentalities and combinations pointed out in the appended claims. Accordingly, the invention resides in the novel steps, operations, parts, constructions, arrangements, combinations and improvements herein shown and described.